Performance Comparison and Migration
性能比较与迁移
What you’ll learn: How to think honestly about JVM performance versus Rust native performance and when migration is actually justified.
本章将学习： 如何诚实地比较 JVM 性能和 Rust 原生性能，以及什么时候迁移才真的说得过去。Difficulty: 🟡 Intermediate
难度： 🟡 中级
Rust often wins on startup time, memory footprint, and tail-latency predictability. Java often wins on mature libraries, team familiarity, and framework productivity.
Rust 通常在启动时间、内存占用和尾延迟可预测性上更强；Java 则常常在成熟库、团队熟练度和框架生产力上更占优。
Where Rust Usually Wins
Rust 通常更强的地方
- startup time
启动时间。 - binary distribution simplicity
二进制分发更简单。 - memory footprint
内存占用更小。 - predictable latency under load
负载下延迟更可预测。
Where Java Still Holds Up Well
Java 依然很能打的地方
- large business systems with mature Spring-based workflows
基于 Spring 的大型业务系统。 - teams optimized for JVM tooling and operations
已经围绕 JVM 工具和运维体系优化好的团队。 - applications where throughput is fine and developer speed matters more than native efficiency
吞吐已经够用，而开发速度比原生效率更重要的应用。
Migration Rule
迁移规则
Benchmark the actual workload before declaring victory. Replace hype with measurements:
先测真实负载，再谈胜利。别拿情绪和口号替代测量：
- p50 and p99 latency
p50 和 p99 延迟。 - memory use
内存占用。 - startup time
启动时间。 - deployment complexity
部署复杂度。
Rust is strongest when it solves a concrete operational pain, not when it is adopted as an aesthetic preference.
Rust 最强的时候，是它在解决一个明确的运行问题，而不是被当成审美选择时。